Abstract: Maxie Aand Zhenshan 97Awere crossed with Minghui 63.Their hybrids were backcrossed with Maxie Band Zhenshan₉₇Brespectively.The F₁, F₂ and BF₁ plants were sown and identified by means of bagged seed setting rate, natural seed setting rate, pollen fertility and individual-observed fertility in field.The genetics of sterility of Maxie Aand Zhenshan 97Awere comparatively studied.The results show that their Sterility is controlled by two pair genes. But the intertiction of those genes in Maxie Ais different from that in Zhenshan 97A, which appears to be dominant epstasis. The fertility segregation of the former comforms with geneticical ratio of 9:3:3:1 in F₂, 1:2:1 in BF₂, the later, 12:3:1 and 2:1:1 in the respective populations. Smirnov tests indicate the frequency distribution of seed setting ratio in F₂ of Maxie A/Minghui 63 and Zhenshan 97A/Minghui 63 is different(P< 0.01).The genefic mechanism and molecule basis of cytoplasmic male sterility are discussed.